xen-blkfront: Handle discard requests.
If the backend advertises 'feature-discard', then interrogate
the backend for alignment and granularity. Setup the request
queue with the appropiate values and send the discard operation
as required.
Signed-off-by: Li Dongyang <lidongyang@novell.com>
[v1: Amended commit description]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index b536a9c..52076b0 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -98,6 +98,9 @@
unsigned long shadow_free;
unsigned int feature_flush;
unsigned int flush_op;
+ unsigned int feature_discard;
+ unsigned int discard_granularity;
+ unsigned int discard_alignment;
int is_ready;
};
@@ -302,29 +305,36 @@
ring_req->operation = info->flush_op;
}
- ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
- BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
+ if (unlikely(req->cmd_flags & REQ_DISCARD)) {
+ /* id, sector_number and handle are set above. */
+ ring_req->operation = BLKIF_OP_DISCARD;
+ ring_req->nr_segments = 0;
+ ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
+ } else {
+ ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
+ BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
- for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
- buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
- fsect = sg->offset >> 9;
- lsect = fsect + (sg->length >> 9) - 1;
- /* install a grant reference. */
- ref = gnttab_claim_grant_reference(&gref_head);
- BUG_ON(ref == -ENOSPC);
+ for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
+ buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
+ fsect = sg->offset >> 9;
+ lsect = fsect + (sg->length >> 9) - 1;
+ /* install a grant reference. */
+ ref = gnttab_claim_grant_reference(&gref_head);
+ BUG_ON(ref == -ENOSPC);
- gnttab_grant_foreign_access_ref(
- ref,
- info->xbdev->otherend_id,
- buffer_mfn,
- rq_data_dir(req) );
+ gnttab_grant_foreign_access_ref(
+ ref,
+ info->xbdev->otherend_id,
+ buffer_mfn,
+ rq_data_dir(req));
- info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
- ring_req->u.rw.seg[i] =
- (struct blkif_request_segment) {
- .gref = ref,
- .first_sect = fsect,
- .last_sect = lsect };
+ info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
+ ring_req->u.rw.seg[i] =
+ (struct blkif_request_segment) {
+ .gref = ref,
+ .first_sect = fsect,
+ .last_sect = lsect };
+ }
}
info->ring.req_prod_pvt++;
@@ -399,6 +409,7 @@
static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
{
struct request_queue *rq;
+ struct blkfront_info *info = gd->private_data;
rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
if (rq == NULL)
@@ -406,6 +417,13 @@
queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
+ if (info->feature_discard) {
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
+ blk_queue_max_discard_sectors(rq, get_capacity(gd));
+ rq->limits.discard_granularity = info->discard_granularity;
+ rq->limits.discard_alignment = info->discard_alignment;
+ }
+
/* Hard sector size and max sectors impersonate the equiv. hardware. */
blk_queue_logical_block_size(rq, sector_size);
blk_queue_max_hw_sectors(rq, 512);
@@ -722,6 +740,19 @@
error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
switch (bret->operation) {
+ case BLKIF_OP_DISCARD:
+ if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
+ struct request_queue *rq = info->rq;
+ printk(KERN_WARNING "blkfront: %s: discard op failed\n",
+ info->gd->disk_name);
+ error = -EOPNOTSUPP;
+ info->feature_discard = 0;
+ spin_lock(rq->queue_lock);
+ queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
+ spin_unlock(rq->queue_lock);
+ }
+ __blk_end_request_all(req, error);
+ break;
case BLKIF_OP_FLUSH_DISKCACHE:
case BLKIF_OP_WRITE_BARRIER:
if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
@@ -1098,6 +1129,33 @@
bdput(bdev);
}
+static void blkfront_setup_discard(struct blkfront_info *info)
+{
+ int err;
+ char *type;
+ unsigned int discard_granularity;
+ unsigned int discard_alignment;
+
+ type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
+ if (IS_ERR(type))
+ return;
+
+ if (strncmp(type, "phy", 3) == 0) {
+ err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+ "discard-granularity", "%u", &discard_granularity,
+ "discard-alignment", "%u", &discard_alignment,
+ NULL);
+ if (!err) {
+ info->feature_discard = 1;
+ info->discard_granularity = discard_granularity;
+ info->discard_alignment = discard_alignment;
+ }
+ } else if (strncmp(type, "file", 4) == 0)
+ info->feature_discard = 1;
+
+ kfree(type);
+}
+
/*
* Invoked when the backend is finally 'ready' (and has told produced
* the details about the physical device - #sectors, size, etc).
@@ -1108,7 +1166,7 @@
unsigned long sector_size;
unsigned int binfo;
int err;
- int barrier, flush;
+ int barrier, flush, discard;
switch (info->connected) {
case BLKIF_STATE_CONNECTED:
@@ -1178,7 +1236,14 @@
info->feature_flush = REQ_FLUSH;
info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
}
-
+
+ err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+ "feature-discard", "%d", &discard,
+ NULL);
+
+ if (!err && discard)
+ blkfront_setup_discard(info);
+
err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
if (err) {
xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
